Sound producer



March 16, 193 7.

SOUND PRODUCER Filed Dec. 13, 1930 2 Sheets-Sheet l /NVENTOR ROBERT L.WILLIAMS A TTORNEY R. L. WILLIAMS V Y 2,073,667 I SOUND PRODUCER FiledDec. 13, 1930 2 SheetS-Sheet-Z m uu E I M 5 A Passer! WILLIAMS 1ATroRNEY Patented Mar. 16, 193 7 PATENT OFFICE SOUND PRODUCER RobertLongfellow WilliamS,.Newton, Mass.,'assignor to Submarine SignalCompany, Boston Mass., a corporation of Maine Applicant December13,1930, Serial lilo. 502,150

1 Claim.

The present invention relates to sound producers and more particularlyto sound producers electrically operated for producing sounds of greator small intensity.

5 Sound producers of this general type are known in the art and havebeen used as fog horns or sirens. In the present case my invention is animprovement onthe device disclosed in my copending applications SerialNo. 288,705, filed June 27, 1928, Patent No. 1,923,959, issued August22,

1933, Serial No. 365,385, filed May 23, 1929, Patent No. 1,977,663,issued October 23, 1934, and Serial No. 403,812, filed October 31, 1929,and has for its object to obtain a more powerful sound produceroperating more efficiently and with greater reliability under allconditions particularly under strenuous service conditions.

The objects and advantages of the present invention will not here beenumerated separately for they will be more readily understood andappreciated when brought forth in connection with the description of theembodiment of the invention as shown in the drawings in which Figure 1shows a view of the invention with a part of the casing removed; Figure2 shows a section of the device shown in Figure 1; and Figure 3 shows adetail of the magnetic system.

In the sound producer as shown in the drawings there is provided acenter element I which has formed as an integral part thereof a base 2adapted to support the whole device. The center element I is composed ofa ring portion 8 having two inwardly extending sectors or elements 3upon which is mounted the electromag netic coil 4 for producing theelectrical forces operating the sound producer. The inwardly extendingportions 3, the ring 8 and the base 2, as indicated in Figure 2, form anintegral piece which may be cast or forged as desired.

The coil 4 is supported in place by clamping arms 5 extending partlyaround the coil 4 and bolted by means of bolts 6 to the elements 3. Oneend of the clamping element 5 rests upon a shoulder 1 of the piece 3 andallows thereby the proper desired pressure to be exerted on the coil 4by tightening the bolt 6 to the proper desired tension. I Mounted oneach side of the ring 8 by means of the flat head screws 9, 9 are thediaphragm elements I0, Ill. The diaphragm elements carry at their centerarmatures II, I I which are'shown in greater detail in Figure 3. Thearmatures I I,

II have threaded studs I2, I2 which screw into a slightly bossed sectionat the center of the diaphragm. The armatures II, II are composed 55 ofthree oppositely positioned pole pieces designated respectively I3, I3,I4, I4 and I5, I5. These pole pieces are rectangular in section, asindicated in Figure 1, but are cut on a bias, as shown more specificallyin Figure 3, in which the bias angle is shown as approximately with thehorizontal, although any other suitable angle may be used. The polepieces are so designed that the central elements I4 are double thesectional area of the end elements I3 and i5. It should also be notedthat while the air gaps 10 between the pole pieces I3, I3 and I5, I5extend on one side of a horizontal line that the pole piece I4 extendson the other side of the horizontal line, thus making equal anglesbetween a normal horizontal. In this manner the vertical components ofthe pull of the pole pieces I3 and I5 may be balanced by the verticalcomponent of the pole pieces I4. By this manner of construction it ispossible to provide an air gap having a comparatively low magneticreluctance for a given amplitude of motion of the pole pieces.

As indicated in Figure 1, the coil 4 passes through the slots I6 and I!about the pole pieces I4 and are independently held in place by theclamping means 5, clamping the end portions of the coil 4 exterior ofthe pole pieces so that while the diaphragms I0 vibrate, the coil 4remains stationary.

Bolted to the diaphragm by means of the bolts 20 is a heavy ring 2|which is threaded on the inner side at 22 to accommodate the plate 23carrying the horn Z4 bolted to it by means of the bolts 25. The plate 23has its distance from the diaphragm I9 adjustable by means of the screwthread at 22 and may be clamped in position when final adjustment ismade by means of the clamping washer 26. The plate 23 together with thediaphragm in back of it forms an air chamber, and the proper adjustmentof the plate with respect to this chamber provides a means for making afinal adjustment of the resonance of the system. The resonating chamber21 has at its lowest point a drain hole 28 to allow any water which maysettle in the chamber to be drained out. The diaphragms I0, however,entirely close the inside of the device and form a water tight joint bymeans of the groove 29 and packing ring 30.

Within each of the horns a screen is placed to prevent foreign matter,such as leaves and the like, from getting into the resonator chambers.

The sound producer is preferably operated by alternating current thoughit may be operated by intermittent or pulsating current. The alternatingcurrent passing through the coil 4 intermittently increases the magneticpull between the diaphragms l0 and produces a motion between the same.In practice this motion may be as great as 70 thousandths of an inch ormore and therefore a considerable sized air gap must be provided. When,however, the air gap is large, the current in the coil 4 must be largeto maintain the same flux on account of the increased ,magneticreluctance. comes this difficulty by making the air gap at an angle tothe normal motion and by so balancing the pulls on different air gapsthat there is no sideways force.

Having now described myinventlon, I claim:

A device for producing continuous sound vibrations of large volumecomprising a central circular base element forming a substantial part ofThe present invention evermerit, a chamber being :formed between eachdia-,

phragm and the flange of the base element, a pair ef cooperating coreelements one mounted at the center of each of the diaphragms and one ofthem extending through the aperture in the flange, a coil looselysurrounding said cores and means for fastening-said coil to said flange.

ROBERT 'LONGFELLOW WILLIAMS.

